1. Field of the Invention:
The present invention relates to a refrigeration system for generating a low temperature, and more particularly to a refrigeration system having a vessel in which an amount of liquid helium is contained for cooling a substance such as a superconducting magnet or a Josefson-element.
2 Description of the Related Art:
A conventional refrigeration system of this kind is disclosed, for example, in Japanese Patent Laid-Open Publication No. 61-8570 published without examination on January 16, 1986. In this refrigeration system, a condenser is disposed in a vessel in which an amount of liquid helium is stored as a coolant for refrigerating a substance. Gaseous helium or evaporated helium within the vessel is condensed into liquid helium by the condenser, thereby keeping the level of the liquid helium constant.
However, in the above conventional refrigeration system, the condenser is adjacent to an expansion cylinder at which a very low temperature is generated, with the result that it is difficult to cool a specific substance such as a superconducting magnet or a Josefson-element which must not be affected by vibrations or magnetism.